U.S. farm incomes are likely to drop 8.7 percent in 2017, a fourth consecutive year of declines amid a deep slump in prices for many crops.

Net farm income is expected to fall to $62.3 billion, half of the record $123 billion farmers earned in 2013, the U.S. Department of Agriculture said Tuesday.

The forecast highlights a deepening downturn in the U.S. agricultural economy, brought on by four straight years of bumper corn and soybean harvests that have added to record grain supplies globally. U.S. farmers last year harvested the biggest corn and soybean crops ever: 15.2 billion bushels of corn and 4.3 billion bushels of soybeans.

Crop receipts are projected to ease 0.5 percent this year amid price declines for key U.S. crops, with the exception of soybeans and cotton. Futures prices for soybeans have risen 4.6 percent this year due to strong export demand. Wheat receipts are expected to slide more than 16 percent as prices drop and farmers sell less of the grain.